Glia Maturation Factor (GMF) is a protein factor we isolated from the adult brain that has the ability to enhance the phenotypic expression of normal immature astrocytes in culture. In this proposal we intend to study the effect of GMF on malignant glial cells. A cloned astrocytic cell line transformed by a temperature-sensitive SV40 virus will be used. The cell line behaves as a neoplastic cell at the permissive temperature (33 degrees Centigrade) and as a normal cell at nonpermissve temperature (40.5 degrees Centigrade) so that the same cell line can serve as its own control by being grown at different temperatures. We intend to study the maturation-stimulating effect of GMF at both the nonpermissive and permissive temperatures, and to see if GMF blocks the appearance of some of the neoplastic properties of the cells in a temperature switch from nonpermissive to permissive. The following chemical parameters will be tested: cyclic AMP, cyclic GMP and their cyclases and phosphodiesterases; the brain-specific protein S-100 protein; the astrocytic protein (glial fibrillary acidic protein); the enzyme glycerophosphate dehydrogenase. It is hope that the study will provide some insight into the interaction between the maturation factor and the malignant process. In particular, we are interested to see if the factor brings about a partial reversion of the malignant transformation.